Screen



W. E. BIXBY June 5, 19 62 SCREEN Filed Jan. 26, 1959 INVENTOR. WALLACE E. BIXBY United States Patent Ofiice 3,037,63h Patented June 5, 1962 3,037,630 SCREEN Wallace E. Bixby, 207 Montrose Way, Wellington, Ohio Filed Ian. 26, 1959, Ser. No. 788,942 2 Claims. (Cl. 202-393) This invention relates to a screen construction and more particularly to a non-blinding screen construction suitable for use in coal washing operations, grading or sizing operations, and the like.

A screen assembly of the type herein described typically comprises one or more screen sections mounted on a support, each section including a plurality of parallel metal wire elements of narrow width and relatively great length supported by spaced parallel cross bars. The parallel wires are spaced one from the other so as to permit the passage of liquids, dust and small particles of predetermined size by the screen. The individual screen sections may be of any suitable size, a common size being 8 in length and approximately 3' in width. Often the support for the screen is a vibratory support which shakes the screen and thereby aids the screening operation. These screens and the uses to which they are put are well known in the art.

One of the chief problems associated with the use of screens of this type is the tendency of the screen to blind. The term blind is used with reference to the condition which develops when the openings of the screen are obstructed by material lodged therein.

An object of the present invention is to reduce the tendency to blinding in screens of the type described by tapering the elongate openings or slots in the screen in the direction of their length. The porosity of the screen thus increases along the length of the slots therein.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description.

In the drawing:

FIGURE 1 is a perspective view of a screen constructed in accordance with the present invention.

FIGURE 2 is a section view taken substantially along the line 2-2 of FIGURE 1.

FIGURE 3 is a section view taken substantially along the line 3-3 of FIGURE 1.

FIGURE 4 is an enlarged fragmentary view illustrating a loop formed in one of the wire elements of the screen of FIGURE 1.

Referring to the drawing in greater detail, there is shown in FIGURE 1 a screen formed of an assembly of parallel wire elements 10. The wire elements each comprise straight wire segments 12 connected by closed loops 14. Only a small segment of each wire element 10' is illustrated and it is to be understood that each of the wire elements may comprise a large number of straight segments 12 connected by a large number of loops 14-.

The wire elements 10 are arranged in parallel relation with their loops 14 in juxtaposition. The loops 14 thus cooperate to provide conduits for the receipt of support rods which, for convenience, have been labeled 16a and 16b. Washers 18 are positioned on the ends of the support rods and these ends are threaded to receive nuts 20. The nuts 20 are tightened upon the support rods so as to press the loops 14 into intimate contact. In the drawing, eight wire elements are secured in parallel relation by the support rods. It is to be understood, however, that in actual practice several hundred of the wire elements may be secured together to form a single screen section. As will be noted in FIGURE 1, the loops and the wire elements are similarly formed and oriented such that the straight segments on one side of each support rod are staggered relative to the straight segments on the other side of that support rod.

With reference to FIGURES 2 and 3 it is to be observed that FIGURE 2 illustrates the straight segments 12 of the wire elements in section, the section being taken adjacent the support rod 16a. FIGURE 3 illustrates the same wire elements in section, this time taken adjacent the support rod '16b. These figures demonstrate that, in moving from the support rods 16a to the support rods 16b, the parallel straight segments 12 undergo a change in shape. Adjacent the rod 16a the shape of the rod is essentially trapezoidal with a large base 22, a small rounded base 24, and convergent sides 26 and 28. Adjacent the support rod 16b, the straight segments 12 have essentially the same cross sectional area, however, the bases have been shortened and the sides have been elongated. -In consequence of this change in shape, the spacing between the straight segments 12 increases from a minimum adjacent the rod 16a to a maximum adjacent the rod 16b.

The changing cross section in the wire elements 10 may be produced by stamping or any other suitable means. As one example, essentially round wire may be advanced through a machine which places the loops 14- in the wire at spaced intervals. In association with this machine, a press may be used to stamp the looped wire to the desired shape. In such a stamping operation, the loops "14 would be compressed to a predetermined thickness where the wire crosses itself, thus determining the center-to-center distance between the wire elements. Simultaneously, the stamping dies would impart the trapezoidal shape to the straight portion 12 and produce the taper therein. Preferably, the looped wire elements are formed continuously with the straight portions between each pair of loops being similarly shaped. Thus, a screen formed of these wire elements will have a large number of tapered slots, there being one slot formed between each pair of adjacent wire elements between each pair of adjacent support rods. Numerous other methods for forming the looped wire elements will occur to those skilled in the art.

In conventional use of screens such as described herein, the material which is to be treated (coal which is to be washed, for example) is caused to flow lengthwise along the screens. In accordance with this practice the present screen is arranged so that the material flows along the screen in the direction of increasing slot width. This is from the left end to the right end of the screen as viewed in FIGURE 1. With this arrangement, small particles which would tend to clog the smaller end of each of the tapered slots in the screen are driven by the flowing material to the larger end of the tapered slot until they drop through the slot or, in the case of particles too large to drop through the slot, until they are carried out of the slot by coaction with the crossed portions of the wire elements at the loops 14. Thus, FIGURE 4 illustrates a particle 30, exaggerated in size, traveling from left to right in a slot about to earn upwardly out of the slot by coaction with a curved portion of wire at the end of the slot. Through this type of operation, particles which are of such a size that they tend to become clogged in the slots are freed due to the diverging sides of the slots.

In screens used in coal washing operations the spacing between the wire elements which form the screen is conventionally in the range extending from .015 to .030". In the screen of this invention slots which taper between maximum and minimum widths within this range are employed.

Although the preferred embodiment of the device has been described, it will be understood that within the pur View of this invention various changes may be made in 89 the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In a wire screen, a plurality of continuous wire elements each comprising a series of elongate similarly shaped segments connected by depending closed loops, the loops of one element lying in juxtaposition to the loops of those on either side thereof, said loops cooperating to form spaced parallel conduits extending substantially normal to the wire elements, support rods disposed in said conduits and means for engaging the ends of said rods for drawing the loops into intimate engagement, adjacent pairs of support rods and loops cooperating to support the elongate segments of the wire elements therebetween at fixed center-to-center separations and in a common plane whereby a plurality of parallel, elongate slots are formed, there being one slot between each pair of adjacent wire elements between each pair or" support rods, there being an equal number of similarly shaped slots between each pair of adjacent support rods and the slots between adjacent pairs of support rods being similarly shaped, each elongate segment having a width in said plane which decreases along its length from one loop to the next whereby each of said slots increases in width along its length, said slots terminating at the loops in said wire elements, the loops at the ends of said slots providing curved surfaces for guiding material flowing along said slots outwardly of said slots.

2,. The structure of claim 1 wherein the elongate segments each have a substantially trapezoidal cross section with parallel large and small bases and with sides which converge toward the small bases, the large bases being disposed in said plane and the small bases being disposed below said plane.

References Cited in the file of this patent UNITED STATES PATENTS 1,942,948 Booth Jan. 9, 1934 2,290,434 Johnson July 21, 1942 2,600,508 Lehman June 17, 1952 2,690,265 BiXby Sept. 28, 1954 

